TB42 running on 4 cylinders?

[4 by 4]

Bit of an update.. Ran 12v straight from the battery to the coil and bypassed the resistor and then checked all the leads/plugs were firing. Found that while on 12v cyl 2 was firing, however when removing the lead the change in engine rpm isnt quite as noticeable as 3/4/5/6. It ONLY did this on petrol. So I'm just taking a guess here but, leaking intake manifold somewhere around 1+2? Because gas is more pressurized than petrol it would be able to leak out easier, meaning that the cyls would still be getting fuel, just no where near as much?

[taslucas]

When I bought the car it was running about 25 advance which amazed me.. so I have backed it off to 14 at the moment but I will double check it tomorrow. It didn't seem to make a lot of difference either.

25 degrees advanced would be for the gas. Gas needs it more advanced than petrol. Putting back to 14 degrees may have a negative effect when running on gas.

[4 by 4]

25 degrees advanced would be for the gas. Gas needs it more advanced than petrol. Putting back to 14 degrees may have a negative effect when running on gas.

He said it was tuned more so for gas but even on 25 advance it ran not too bad on petrol.

[taslucas]

He said it was tuned more so for gas but even on 25 advance it ran not too bad on petrol.

Yes but putting it back to 14 advanced probably run that well on gas.

[Parksy]

Bit of an update.. Ran 12v straight from the battery to the coil and bypassed the resistor and then checked all the leads/plugs were firing. Found that while on 12v cyl 2 was firing, however when removing the lead the change in engine rpm isnt quite as noticeable as 3/4/5/6. It ONLY did this on petrol. So I'm just taking a guess here but, leaking intake manifold somewhere around 1+2? Because gas is more pressurized than petrol it would be able to leak out easier, meaning that the cyls would still be getting fuel, just no where near as much?

Replace the intake gasket, use some spray on sealant just to be sure. Might be a pain for a few hours(by doing it I mean) but then it might solve your issue and if not, it's one thing eliminated. Gasket replacement is a cheap fix if you do it yourself.

[4 by 4]

Replace the intake gasket, use some spray on sealant just to be sure. Might be a pain for a few hours(by doing it I mean) but then it might solve your issue and if not, it's one thing eliminated. Gasket replacement is a cheap fix if you do it yourself.

I'll look at doing that probably this weekend. Is there a way to leak test the manifold while it is off?

[davo94]

Really not needed. Just hang the manifold to the side rather than removing if from the car. Its guicker.

[4 by 4]

Found my problem tonight! Was a leaking intake manifold gasket around cyl 1 and the thermostat housing, but it was only leaking on the underside which took alot of messing around to find (even after 3 attempts to find vac leaks in the previous days) Gasket was pretty well rooted and was crumbling away, which is strange because it looked very old but the head was replaced in 2010, I would have thought they would have done the intake at the same time but oh well. Decided to take entire manifold off which was a PITA but since I knew it wasnt going to be finished tonight I'd rather have it off and block off the intake holes to the motor than leave a manifold dangling in the engine bay.

Thanks for the help everyone especially Parksy

Quick question also, should I fork out the 60 or so dollars for a new gasket or would gasket maker be better/just as good? Im happy to pay the money for a gasket if its the better option

[Robo]

Gasket with some ,hylomer seleant on it.
Hylomer will help to prolong the gaskets life.
Also forms a better seal at the same time.
Not cheap $20+ but small can goes a fair way.

[Parksy]

Happy days, glad you've found the problem. If you still have the manifold off now is a good time to check you don't have a leaking oil cooler/blanking plate (which ever is fitted). Doesn't use a gasket, just silicone, but a pain in the backside to change if the manifold is fitted. Located between the starter motor and the intake on the block.